Enhanced welding device

ABSTRACT

The present invention relates to a welding device suitable for joining by welding a first and a second part at a weld joint, said parts defining a joint face between said parts, the device comprising: a traveling support mean ( 2 ) for moving the device along the weld joint; at least one welding means ( 4 ) cooperating with said traveling support means ( 2 ) so as to be kept at a distance from said weld joint; means for automatic motion control of the traveling support mean ( 2 ) in particular. 
     According to the invention, said at least one welding means is mounted on a single supporting piece ( 3 ) facing substantially parallel with said joint face; the device further comprises a first motorized actuator ( 5 ) attached to said traveling support means ( 2 ) and provided with a first protuberance ( 51 ) cooperating with a first seating ( 52 ) open onto a first end face of said single supporting piece ( 3 ); a second motorized actuator ( 6 ) attached to said traveling support means ( 2 ) and provided with a second protuberance ( 61 ) cooperating with a second seating ( 62 ) open onto a second end face of said single supporting piece ( 3 ) such that said first ( 51 ) and second ( 61 ) protuberances are movable in a plane substantially perpendicular to said joint face and generate a control movement of the welding means supporting piece ( 3 ).

FIELD OF THE INVENTION

The invention relates to the field of welding parts by means of various processes consisting of melting materials in order to join parts or produce leak tight seals. The application may extend to all sectors of metal working or other, particularly to the joining of tubular pipes, which need to be welded end to end to form continuous pipes over large distances.

The formation of such structures, whether they consist of flat elements, of any shape or tubular, such as pipelines, is performed by adjoining, with little or no gaps, edges or faces between the elements to be welded, and moving the welding means along the weld line or area defined.

If a seal (on a single or between a plurality of parts) is required, the welding means should be moved along the lines to be sealed.

The invention relates to the kinematics of the welding means supporting piece which is moved along the weld area or line. This movement may be made by any type of traveling support means whether it is a robot or rail-mounted carriage, wheeled vehicle or other designs according to the application envisaged.

The welding means are elements for the use of various welding processes on the part such as TIG, MIG, MAG, laser, etc.

All construction operations between metallic parts require welding quality compatible with the required criteria to ensure personal safety and installation reliability.

The production of pipeline type assemblies are carried out by placing a plurality of tubes or pipes having substantially the same cross-sections in a end to end position, and producing an annular weld between two pipe ends positioned in this way, and so on. According to a known off-shore or on-shore practice, some pipes lengths are thus welded together, transported to the operating site, positioned and then welded to a pipe already in place.

In off-shore applications, these prefabrications may be carried out directly on the ship. It is obvious that the welds need to be of very high quality to withstand both during the transport period and particularly during pipeline operation where the environmental conditions (high pressures for example) are frequently severe and were fluids containing all kinds of corrosive constituents (gas, oil, sludge, etc.) may circulate inside the pipes.

To form such pipes, it is usual to weld a pipe portion to one end of a set of pipes already welded together, from an off-shore mobile barge. In this context, the barge moves continuously under the effect of heave motion such that the welding is performed under particularly difficult conditions.

Furthermore, the weight of the pipes and thus the stress involved are considerable, each pipe potentially weighing several hundred kilograms or several tens of tons. The welding quality is thus a decisive factor for the service life of the pipes and for the reliability and/or safety thereof. The quality of the initial weld is also very important for production: indeed, a weld detected as having defects needs to be repaired which disturbs the production cycle.

Numerous solutions have been developed over many years to remedy this type of problems.

In the case of pipeline welding, a particular problem arises when welding the outermost layer of the weld bead which is thus inserted and fills the annular space defined between two tube or pipe ends. This final step is known as “capping” in the field.

More specifically, the annular space between the ends of two pipes may have a V- or U-shaped cross section. In a known manner, the weld is deposited from the base of the V or U to the ends corresponding to the zone closest to the outer wall of the pipes to be welded. At this point, the distance between the edges of the pipes is the greatest, generally requiring the formation of two side-by-side weld beads in order to fill this space. When two welding means are present to form the seal at this point, an adjustment is thus required to offset (i.e. along the longitudinal axis of the pipes to be welded) the welding means laterally with respect to each other. In a known and routine manner, this adjustment is performed manually by an operator; obviously, this adjustment takes time which is always precious and thus costly in terms of production.

The known prior art does not suggest any modification for simplifying and/or enhancing such welding means.

STATE OF THE RELATED ART

The document U.S. Pat. No. 3,974,356 envisages a welding assembly external to the pipes to be welded and comprising two welding means arranged one behind the other in the direction of circumferential movement, along the weld. Each of the welding means may oscillate independently from the other, with different amplitudes. A complex mechanism makes it possible to support and also manually adjust the position of each of the welding means. This embodiment advantageously makes it possible to produce two parallel weld beads in a single pass, which saves time compared to systems only having a single head, but a manual head adjustment problem arises in this instance. Furthermore, not all the head orientations can be obtained with such a system. Due to the intrinsic design of this system, the oscillation movements produced by both welding means about the longitudinal weld axis are the same.

The U.S. Pat. No. 3,748,426 is also known, describing an assembly comprising three welding heads mounted on the same supporting piece, offset in the direction of circumferential movement, which can oscillate independently from each other, in which the radial position is independently and manually adjustable. With this type of technical solution, it is only possible to obtain differentiated oscillation of each head perpendicular to the joint face; this thus involves manual adjustments as mentioned above, which are both costly and difficult. Furthermore, not all the particular movements, such as pendulum type movements, can be obtained with this prior solution.

DESCRIPTION OF THE INVENTION

The invention aims to remedy the drawbacks of the prior art and particularly propose a welding assembly offering advantageous, innovative and unexpected modularity and simplicity.

For this purpose, according to a first aspect, a welding device is proposed, suitable for joining by welding a first and a second part at a weld joint, said parts defining a joint face between said parts, the device comprising: a traveling support mean for moving the device along the weld joint; at least one welding means cooperating with said traveling support mean so as to be kept at a distance from said weld joint; means for the automatic motion control of (in particular) the traveling support mean.

According to the invention, said at least one welding means is mounted on a single supporting piece substantially parallel with said joint face, and the device further comprises a first motorized actuator attached to said traveling support mean and provided with a first protuberance engaging with a seating open onto a first end face of said single supporting piece; a second motorized actuator attached to said traveling support means and provided with a second protuberance cooperating with a seating open onto a second end face of said single supporting piece such that said first and second protuberances are movable in a substantially perpendicular plane to said joint face and generate a controlled movement of the welding means supporting piece.

It is thus possible to produce varied controlled movements of the welding means by means of a single control means which in this instance controls two actuators, the movements whereof are combined in different ways to generate specific welding head (or welding means) movements.

The prior art does not disclose or suggest this technical solution which particularly simplifies welding head (or means) adjustment.

In particular, said motion control means may enable a simultaneous linear movement of said first and second protuberances in the same direction. In this case, this makes it possible to offset the central oscillation axis of each torch and produce two parallel weld beads. This aspect is advantageous and necessary when producing capping external finish welds on tubular pipes. In the second case, very advantageous oscillation effects as explained below may be obtained.

Also very advantageously, said motion control means enables simultaneous linear movement of said first and second protuberances in two opposite directions, so as to create a rotation of the welding means supporting piece about a substantially perpendicular axis to the weld joint. This feature thus enables rotation of the welding means supporting piece without requiring the presence of a specific axis of rotation. The gain is very advantageous in terms of production simplicity, cost, maintenance, etc. This rotation movement advantageously makes it possible to extend the kinematic capabilities of the oscillations.

The motion control may be performed by means of a microcomputer preprogrammed for the various type of motion mentioned above. Any equivalent technical means may be used without leaving the scope of the invention.

Furthermore, the motion control means can make it possible to independently change the movement amplitude of the first and/or second protuberance. This aspect makes it possible to obtain welding means movements that are controlled, precise while being different and suitable for each application. The thus formed welds will be more precise and of superior quality; furthermore, they will be produced in shorter times particularly due to the absence of operator intervention.

A further option offered by the invention lies in that the welding device comprises means for varying the distance between said welding means and the weld joint; said supporting piece may thus be arranged more or less near the outer wall of each of the parts to be welded.

According to a further feature, the device may comprise means for individually varying the distance between at least one first and/or at least one second welding means and said weld joint. Once again, this feature makes it possible to optimally adjust and adapt the device to the type of weld to be produced, and to the geometry of the parts to be welded, particularly in the case of tubular pipes.

According to an additional feature of the invention, the device comprises containment means situated between the supporting piece and the weld joint.

More specifically, these means may comprise at least one flange or plate cooperating with the supporting piece and defining a confinement volume together. This is merely one of the options offered for producing a confinement space corresponding to the required gas protection between the electrode and the parts to be joined, particularly in the case of TIG, MIG or MAG welding.

Furthermore, the device according to the invention may comprise at least one sensor attached on at least one of the components of the device, for measuring the position of said sensor with respect to the weld joint. This particularly makes it possible to centre at least one of said welding means with respect to the joint face.

This feature is an advantageous arrangement in that it increases the precision and quality of the weld obtained.

Preferably, said parts to be joined by welding have at least one annular cross-section.

BRIEF DESCRIPTION OF THE FIGURES

Further features, details and advantages of the invention will emerge on reading the following description, with reference to the appended figures, illustrating:

FIG. 1, a perspective view of a welding device according to the invention;

FIG. 2, a front view of a welding device according to one embodiment of the invention;

FIG. 3, a bottom view of a welding device according to one embodiment of the invention;

FIG. 4A is a schematic view of a device according to the invention in a characteristic position of a first operating mode;

FIG. 4B is a schematic view of a second operating mode;

FIG. 5 is a simplified perspective view of a device according to the invention positioned on traveling carriage engaging with an circular rail; and

FIG. 6 is a simplified perspective view of a device according to the invention positioned on traveling carriage engaging with an circular rail.

For more clarity, identical or similar elements are referenced with identical reference signs in all the figures.

DETAILED DESCRIPTION OF AN EMBODIMENT

According to the invention illustrated in FIGS. 1 and 2 in particular, the welding device comprises welding means 4, in this instance consisting of two torches (or means) 41,42, borne by a single supporting piece 3 having a substantially parallelepiped shape wherein the two large areas are planes facing parallel with a joint face P, such that both welding means 41,42, are arranged one behind the other in the direction of (circumferential) movement of the carriage 2 on the rail 1. In this instance, the supporting piece 3 has a suitably oriented axis of symmetry XX with respect to the pipes to be welded.

Furthermore, the single supporting piece 3 has at least one first 52 and one second groove or seating 62 each opening onto one of the “side” faces thereof, i.e. perpendicular to the two main faces thereof. Each of the side faces thus extends substantially perpendicular to the joint face. Each groove 52,62 has a cross-section such that a first eye bracket 51 and a second eye bracket 61, respectively, can be housed therein.

The term eye bracket refers to a protuberance having an orifice wherein an axis actuated by a translation movement is housed.

The first eye bracket 51 is part of a first linear motorized actuator 5 onboard the carriage 2 applying a linear to-and-from motion thereto; the second eye bracket 61 is part of a second motorized linear actuator 6 applying a linear to-and-from motion thereto. In the case of tubular pipe welding, the first 51 and the second 61 eye brackets are movable in a substantially circumferential trajectory about the pipes to be welded. They induce a specific controlled movement of the supporting piece 3. The eye brackets comprise, in relation to the parts with which said eye brackets engage, a mechanical clearance necessary for the proper operation of the device.

Advantageously, according to the combination of movements of said eye brackets 51, 61, the single supporting piece 3 is moved in a predetermined way as explained hereinafter.

Each actuator 5, 6 may consist of a housing containing a drive system, provided with a protruding eye bracket as specified above. The housing is onboard, i.e. connected to the carriage 2, by any means known per se. According to the embodiment illustrated in the figures, each actuator is bolted on a frame 7 which is in turn attached to the carriage 2.

With respect to the motion control of the actuators, if both eye brackets 51, 61 are moved simultaneously in the same direction and with the same amplitude, the supporting piece 3 and both welding means 41, 42 will oscillate together according to a so-called lateral movement, the amplitude whereof is advantageously adjustable. FIG. 4A illustrates such positioning. In this way, two annular weld beads superimposed according to the thickness of the weld may be formed. The innermost bead is formed by the welding means 41 or 42 positioned ahead in relation to the direction of movement of the carriage 2; the outermost bead of the pass is formed by the welding means 41 or 42 positioned behind the other.

If both eye brackets 51, 61 are moved simultaneously in the same direction and with an identical amplitude and different centering, the supporting piece 3 and both welding means 41,42, will oscillate together according to a lateral movement and two parallel weld beads will be laid; this is particularly advantageous for finishing-coating passes referred to as capping.

If both eye brackets 51, 61 are moved simultaneously in the same direction and with a different amplitude, the supporting piece 3 and both welding means 4 will oscillate together according to a lateral movement and two parallel weld beads will be laid, as described above; in this instance, one is wider than the other.

If both eye brackets 51, 61 are moved simultaneously in opposite directions and with the same amplitude, the supporting piece 3 will be actuated by a rotational movement in relation to the axis of symmetry XX thereof, such that the weld beads obtained may be aligned or laterally offset i.e. according to the longitudinal axis of the pipes to be welded. FIG. 4B illustrates the corresponding positioning of the supporting piece 3.

If both eye brackets 51, 61 are moved simultaneously in two opposite directions and with a different amplitude, the supporting piece 3 will be actuated by a rotational movement in relation to the axis of symmetry XX thereof, and the weld beads obtained with the first 41 and the second 42 welding means, respectively, may be aligned or laterally offset, one being wider than the other. The centre of rotation of the part 3 may be moved along the axis of symmetry thereof according to these relative amplitudes. Obviously, FIG. 4B shows the positioning of the supporting piece 3 in such an operating mode.

Without leaving the scope of the invention, more than two welding means may be provided. Those skilled in the art will choose according to the application in question.

Motion control means are provided for producing either kinematics, as described above as an illustration. As already mentioned, this means may comprise a programmable microcomputer or any equivalent means. Remote and wireless controls may be provided to control the welding operation procedure.

A single welding means positioned at the centre of the supporting unit 3 may have a perfectly rotary oscillation movement. One or a plurality of welding means having a non-perpendicular angle of inclination to the trajectory parallel with the joint face will have a movement comparable to pendulum type oscillation. When the welding means is/are facing the walls of the joint to be welded, it/they will have a similar pitch angle to that supplied by pendulum type oscillation.

Furthermore, it may be envisaged, without leaving the scope of the invention, to provide a specific motor for moving the supporting piece 3 along the axis of symmetry XX thereof. This feature thus makes it possible to move said supporting piece 3 closer or further away with respect to the weld joint. The effect induced by this feature will be appreciated in the case of narrow gap bevels, forming small angles with each other.

It is also possible to envisage individual motorization for each welding head 4, thus enabling a differentiated movement of each head along their longitudinal axis thereof. Although this solution complicates system management somewhat, it falls within the scope of the invention.

Advantageously, particularly in the case of MIG or MAG welding, it is important to provide a specific gaz protection between the electrode wire and the material to be welded. For this purpose, the device according to the invention may comprise containment means for defining and closing this space.

According to one embodiment, plates or flanges 10, 10′ are attached on the outer walls of the welding means supporting piece 3. These plates define with the weld joint placed in the vicinity a substantially parallelepiped confined space. The molten metal can thus be isolated from the ambient air simply and effectively.

An additional feature of the invention consists of providing the device with at least one sensor preferentially arranged in the vicinity of the weld joint, for assessing the position of the sensor in relation to the weld joint. This may particularly enable centering of the axis of symmetry of the unit 3. The use of two sensors at each end of the unit 3 may provide superior centering by enabling the axis of the unit 3 to merge with the axis of the weld seam.

FIG. 5 consists of a perspective view of the device according to the invention in position with respect to the parts to be welded, which are tubular pipes in this instance. Indeed, a portion of circular rail 1 can be seen therein. The rail 1 is attached by any means known per se and not shown, around the outer wall of a tubular pipe; more specifically, the circular rail 1 is attached in the vicinity of the joint face between two pipes to be welded together.

The joint face is defined as the plane in the middle of the end surfaces of each of the parts or pipes to be welded. The parts or pipes are positioned and then locked together by any clamping or tightening means known per se. This aspect will not be described further. When joining tubular pipes, the end surfaces generally define a ring wherein the inner diameter consists of the (substantially identical) inner diameter of the two pipes to be welded. The edges of the pipes are preferentially beveled, frequently with a root, such that the weld is V- or U-shaped, with the root face generally perpendicular to the longitudinal axis of the pipes to be welded. Various bevel shapes may be processed with a device according to the invention.

Conventionally and preferably, automatic pipe welding is performed using a MIG or MAG method, arc welding methods known per se wherein the metals are melted by the heat energy released by an electric arc which explodes in a so-called protective atmosphere, between a fusible electrode wire and the parts to be joined; more specifically at the joint face. The difference between the MIG and MAG methods lies in the composition of the gas contained in the protective atmosphere.

According to the MIG method, a neutral gas such as Argon or Argon and Helium is used, which thus does not react with the metals to be welded; according to the MAG method, a mixture of Argon, carbon dioxide and hydrogen is used. In any case, the gas is continuously injected onto the arc in order to completely isolate the molten metal in relation to the ambient air. The quality of the weld is closely dependent on the degree of isolation of the molten metal during welding. Various gas supplies are thus provided for the operation of any welding device of this type.

Without leaving the scope of the invention, TIG welding may be carried out; furthermore, laser welding may be performed with a device according to the invention.

According to FIG. 5, the carriage or traveling support means 2 is attached to and movable on an circular rail 1. The carriage 2 comprises all the onboard means necessary for the operation and control of the welding means. The carriage 2 is attached to the rail 1 by wheels or any equivalent means enabling said carriage to be both movable and held on the rail 1. FIG. 6 illustrates very schematically the connection between the traveling support means 2 and the rail 1.

The rail-mounted carriage is a specific traveling support means, which would be different in the case of a robot.

The means onboard the traveling support means particularly comprise the supporting piece, electrical and gas connections and of course the welding means 4 kept at a substantially constant radial distance from the weld joint. The structural arrangements in the choice, positioning and connections between these means remain up to those skilled in the art. 

1. Welding device suitable for joining by welding a first and a second part at a weld joint, said parts defining a joint face between said parts, the device comprising: a traveling support means for moving the device along the weld joint; at least one welding means cooperating with said traveling support means so as to be kept at a distance from said weld joint; means for the automatic motion control of the traveling support means in particular characterized in that said at least one welding means is mounted on a single supporting piece substantially parallel with said joint face, in that the device further comprises a first motorized actuator attached to said traveling support means and provided with a first protuberance cooperating with a first seating open onto a first end face of said single supporting piece; a second motorized actuator attached to said traveling support means and provided with a second protuberance cooperating with a second seating open onto a second end face of said single supporting piece such that said first and second protuberances are movable in a substantially perpendicular plane to said joint face and generate a control movement of the welding means supporting piece.
 2. Device according to claim 1 wherein said motion control means enables a simultaneous linear movement of said first and second protuberances in the same direction.
 3. Device according to claim 1 wherein said motion control means enables simultaneous linear movement of said first and second protuberances in two opposite directions, so as to create a rotation of the welding means supporting piece about a substantially single perpendicular axis to the weld joint.
 4. Device according to claim 2 or claim 3 wherein the motion control means make it possible to independently change the movement amplitude of the first and/or second protuberance.
 5. Device according to claim 1 or 2 further comprising means for varying the distance between said welding means and the weld joint.
 6. Device according to claim 1 or 2 further comprising means for individually varying the distance between at least one first and/or at least one second welding means and said weld joint.
 7. Device according to claim 1 further comprising containment means situated between the supporting piece and the weld joint.
 8. Device according to claim 7 wherein said containment means comprise at least one flange cooperating with the single supporting piece and defining a confinement volume together.
 9. Device according to claim 1 further comprising at least one sensor attached on at least one of the components of the device, for measuring the position of said sensor with respect to the weld joint.
 10. Device according to claim 1 wherein said parts to be joined by welding have at least one annular cross-section. 